This week started with holiday travel and gatherings threatened by the surging Omicron variant. Since Omicron was first named a variant of concern (VOC) on November 26 by the World Health Organization, we have learned much about its alarming transmissibility and immune escape but only a little about its virulence. The latter will be key in determining the impact of Omicron. Its transmissibility and the reduced effectiveness of vaccine-induced and natural immunity against it will bring a rapid increase in infections and COVID-19 cases. Whether our healthcare system can handle the load will depend on the severity of the COVID-19 cases it causes.  

Emerging evidence has been captured and summarized by several agencies including the UK Health Security Agency in its “Technical briefing 32,” the European Centre for Disease Prevention and Control in its December 15 “Rapid Risk Assessment,” and the World Health Organization in its December 15 “Technical Brief and Priority Actions for Member States.” These syntheses and other reports provide consistent and conclusive documentation of the high transmissibility of the Omicron versus the Delta variant with a doubling time of 1.5-3 days. In South Africa, Denmark, and the United Kingdom, sharp increases in Omicron cases have occurred. Such growth may be occurring in Colorado, as we have moved from a handful of cases last week to the rapid rise now evident this week. Omicron is likely to quickly take over.  

The evidence of immune escape by the Omicron variant is mounting and disconcerting. A meta-analysis of the studies of neutralizing antibodies shows around a 10-fold drop in neutralization titer against Omicron. That is, circulating antibodies have a substantial drop in their ability to protect against Omicron. A booster shot with one of the existing mRNA vaccines almost restores efficacy to previous levels. This week, there was a consistent call for those eligible to get their booster ASAP, given the threat of Omicron. In Colorado, 40% of those 18 and older, who are eligible to receive a booster dose, have done so, with more becoming eligible as time passes since the second dose. Unfortunately, 22% of Colorado’s adults remain unvaccinated. Governor Polis’ message last week was clear—get a booster shot if you are eligible.

The virulence of the Omicron variant remains the critical uncertainty. The UK Health Security Agency continues to rate the evidence as insufficient to make a determination. While we are still at the start of the Omicron surge, the good news is that there is no indication of greater severity of Omicron versus Delta, so far.  

Omicron has arrived at the wrong time and the right time. The wrong time? The start of holiday travel and the arrival of Omicron coincide. The right time? We are entering the holidays and will have a sufficiently long window of time to understand Omicron’s impact before making decisions about returning to schools and offices. Additionally, the epidemic curve in Colorado has now fallen progressively for four weeks. The number of confirmed COVID-19 hospitalizations dropped from the November 23 high of 1,576 Coloradans hospitalized with COVID-19 on November 23 to 1,086 yesterday. In Colorado, Omicron arrives as Delta is declining rather than rising as in most states at present. Nonetheless, if Omicron surges and its virulence is not greatly lower than that of Delta, the months ahead could prove challenging for Coloradans and for Colorado’s healthcare system. A return to unwanted non-pharmaceutical interventions may be needed, as is already happening in the Netherlands (return to lockdown) and the United Kingdom. Governor Polis was a guest on Meet the Press on Sunday; his comments emphasized the importance of vaccination, particularly a third dose.  

Turning to some good news, I had previously described the stay of implementing the Occupational Safety and Health Administration (OSHA)’s Emergency Temporary Standard (ETS) by the Fifth Circuit Court of Appeals. That stay was reversed last week by the Sixth Circuit. The ETS can now be implemented with its requirement for vaccination or use of protective face coverings and weekly testing in workplaces with 100 or more employees. The opinion draws on public health science, setting aside the plaintiff’s arguments against the ETS and the Fifth Circuit’s superficial attention to the impact of the pandemic on workers.

And the last good news—we are heading for the holidays. However, our colleagues caring for patients are no doubt anxiously waiting to see what Omicron brings in the weeks to come.  Have a restful and safe holiday. By January 1, we will know what the arrival of the Omicron variant means.  

Happy New Year,

Jonathan Samet, MD, MS
Dean, Colorado School of Public Health

This week started with holiday travel and gatherings threatened by the surging Omicron variant. Since Omicron was first named a variant of concern (VOC) on November 26 by the World Health Organization, we have learned much about its alarming transmissibility and immune escape but only a little about its virulence. The latter will be key in determining the impact of Omicron. Its transmissibility and the reduced effectiveness of vaccine-induced and natural immunity against it will bring a rapid increase in infections and COVID-19 cases. Whether our healthcare system can handle the load will depend on the severity of the COVID-19 cases it causes.  

Emerging evidence has been captured and summarized by several agencies including the UK Health Security Agency in its “Technical briefing 32,” the European Centre for Disease Prevention and Control in its December 15 “Rapid Risk Assessment,” and the World Health Organization in its December 15 “Technical Brief and Priority Actions for Member States.” These syntheses and other reports provide consistent and conclusive documentation of the high transmissibility of the Omicron versus the Delta variant with a doubling time of 1.5-3 days. In South Africa, Denmark, and the United Kingdom, sharp increases in Omicron cases have occurred. Such growth may be occurring in Colorado, as we have moved from a handful of cases last week to the rapid rise now evident this week. Omicron is likely to quickly take over.  

The evidence of immune escape by the Omicron variant is mounting and disconcerting. A meta-analysis of the studies of neutralizing antibodies shows around a 10-fold drop in neutralization titer against Omicron. That is, circulating antibodies have a substantial drop in their ability to protect against Omicron. A booster shot with one of the existing mRNA vaccines almost restores efficacy to previous levels. This week, there was a consistent call for those eligible to get their booster ASAP, given the threat of Omicron. In Colorado, 40% of those 18 and older, who are eligible to receive a booster dose, have done so, with more becoming eligible as time passes since the second dose. Unfortunately, 22% of Colorado’s adults remain unvaccinated. Governor Polis’ message last week was clear—get a booster shot if you are eligible.

The virulence of the Omicron variant remains the critical uncertainty. The UK Health Security Agency continues to rate the evidence as insufficient to make a determination. While we are still at the start of the Omicron surge, the good news is that there is no indication of greater severity of Omicron versus Delta, so far.  

Omicron has arrived at the wrong time and the right time. The wrong time? The start of holiday travel and the arrival of Omicron coincide. The right time? We are entering the holidays and will have a sufficiently long window of time to understand Omicron’s impact before making decisions about returning to schools and offices. Additionally, the epidemic curve in Colorado has now fallen progressively for four weeks. The number of confirmed COVID-19 hospitalizations dropped from the November 23 high of 1,576 Coloradans hospitalized with COVID-19 on November 23 to 1,086 yesterday. In Colorado, Omicron arrives as Delta is declining rather than rising as in most states at present. Nonetheless, if Omicron surges and its virulence is not greatly lower than that of Delta, the months ahead could prove challenging for Coloradans and for Colorado’s healthcare system. A return to unwanted non-pharmaceutical interventions may be needed, as is already happening in the Netherlands (return to lockdown) and the United Kingdom. Governor Polis was a guest on Meet the Press on Sunday; his comments emphasized the importance of vaccination, particularly a third dose.  

Turning to some good news, I had previously described the stay of implementing the Occupational Safety and Health Administration (OSHA)’s Emergency Temporary Standard (ETS) by the Fifth Circuit Court of Appeals. That stay was reversed last week by the Sixth Circuit. The ETS can now be implemented with its requirement for vaccination or use of protective face coverings and weekly testing in workplaces with 100 or more employees. The opinion draws on public health science, setting aside the plaintiff’s arguments against the ETS and the Fifth Circuit’s superficial attention to the impact of the pandemic on workers.

And the last good news—we are heading for the holidays. However, our colleagues caring for patients are no doubt anxiously waiting to see what Omicron brings in the weeks to come.  Have a restful and safe holiday. By January 1, we will know what the arrival of the Omicron variant means.  

Happy New Year,

Jonathan Samet, MD, MS
Dean, Colorado School of Public Health